From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE018C433F5 for ; Tue, 2 Nov 2021 09:47:05 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 741B460240 for ; Tue, 2 Nov 2021 09:47:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 741B460240 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id E3FB44B15A; Tue, 2 Nov 2021 05:47:04 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8sjIdMi-l1dI; Tue, 2 Nov 2021 05:47:03 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 279DE4B15E; Tue, 2 Nov 2021 05:47:03 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 88AE64B15E for ; Tue, 2 Nov 2021 05:47:02 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lL0fhGIvfOWO for ; Tue, 2 Nov 2021 05:47:00 -0400 (EDT) Received: from mail-io1-f74.google.com (mail-io1-f74.google.com [209.85.166.74]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id C44B54B153 for ; Tue, 2 Nov 2021 05:47:00 -0400 (EDT) Received: by mail-io1-f74.google.com with SMTP id j19-20020a0566022cd300b005e1816be9abso6929630iow.8 for ; Tue, 02 Nov 2021 02:47:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=8Hd2ZUMx5ILHWyo2zM7pIHkuH4DnNmNsL76fDtWtm1s=; b=E2M0qmyqra/TlmR8sNdUNnqypFAgx2byfZsucj64HcfDQTvxD/mvhZJkXohOyHvfnv d5IB+ZGFXPR88GhGj/Ivf6QeDGp/6YurkWU2p55yIF4wdlt+JGIIU7r6G+HtZB05dFYo CGJuXlvDZLzUfyKYuMfoyq10hlYCDy/eizAOlLOxyNs7nwnVK952aeHGe/7QAwduEmge +I11gM4N4guNIyZWghqOG+A1y17uVCtQQwQhMKCIY5yU3QnKn7qPfbhZl8i+MP/Jd3Kf l3LWpUcJCZ8LPuWIkK9ibOyrEYmODpJ1s/MuMXosi0RdgDOUHSUtMAoyMKpl4/92Jzdp NXJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=8Hd2ZUMx5ILHWyo2zM7pIHkuH4DnNmNsL76fDtWtm1s=; b=yRke+hCDlFlRYmsq3a6Fci3I6vJEOzMRHNzEJSelPjsLFuL43YemeG3m+IbovkIaXI bCFm3amvpnVmV+0K7uhjSWtGDT1teL5XxwatG8PPFrF3eNwaZKe4Gsyr4P8/dqGpIvQ8 g6xXRT/pxDSzFmHrZlrBDL/cV+EHfv+YB1IPuCw9Woapk9dlrwSKY8gRTlHDDONW3kZq VLqT6RDIV1yrkk/8s31ua3HKkQPk7NDvDhpj3gqi1B7quJvK2P9c0JsemT06fhI3yaVV poJNT3nLfURjA7+pzOBpIak7IoqfTvP2ZZqaiStRESNUk+FcEQAnnkuqyNHDKExfJNKt RAkA== X-Gm-Message-State: AOAM530hGGZ+klhZdddAdNqcfAV5F/Pw2IFpA3NDPHnZUB0f4cDgvJnx H6KHZPRBTphTgRdH4npoLuvdThg9CSI421EkX1pQclLHOFTY0wqvGeMMoigvBO5bBXKY0tdCDg5 GEZ/vbXjzOBJ9cduAC72eqDEdmB8dynXqPVt1KnGBS2rV1zBIpUA0qJEft/1kENN+3fDJZw== X-Google-Smtp-Source: ABdhPJwp82eJZKpATb/STfJK1tEYrOYlTSbWGpyQyJFGOHuzO64TyzBAnAXrfYhajH7o5tbhGvqNlILST3A= X-Received: from oupton.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:404]) (user=oupton job=sendgmr) by 2002:a02:c9c1:: with SMTP id c1mr11157225jap.0.1635846420169; Tue, 02 Nov 2021 02:47:00 -0700 (PDT) Date: Tue, 2 Nov 2021 09:46:45 +0000 Message-Id: <20211102094651.2071532-1-oupton@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.33.1.1089.g2158813163f-goog Subject: [PATCH v2 0/6] KVM: arm64: Emulate the OS lock From: Oliver Upton To: kvmarm@lists.cs.columbia.edu Cc: kvm@vger.kernel.org, Marc Zyngier , Peter Shier , linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu KVM does not implement the debug architecture to the letter of the specification. One such issue is the fact that KVM treats the OS Lock as RAZ/WI, rather than emulating its behavior on hardware. This series adds emulation support for the OS Lock to KVM. Emulation is warranted as the OS Lock affects debug exceptions taken from all ELs, and is not limited to only the context of the guest. The 1st patch is a correctness fix for the OSLSR register, ensuring the trap handler actually is written to suggest WO behavior. Note that the changed code should never be reached on a correct implementation, as hardware should generate the undef, not KVM. The 2nd patch adds the necessary context to track guest values of the OS Lock bit and exposes the value to userspace for the sake of migration. The 3rd patch makes the OSLK bit writable in OSLAR_EL1 (from the guest) and OSLSR_EL1 (from userspace), but does nothing with its value. The 4th patch actually implements the OS Lock behavior, disabling all debug exceptions from the perspective of the guest. This is done by disabling MDE and SS in MDSCR_EL1. Since software breakpoint instructions cannot be masked by anything but the OS Lock, we emulate by trapping debug exceptions to EL2 and skipping the breakpoint. Skip this whole song and dance altogether if userspace is debugging the guest. The 5th patch asserts that OSLSR_EL1 is exposed by KVM to userspace through the KVM_GET_REG_LIST ioctl. Lastly, the 6th patch asserts that no debug exceptions are routed to the guest when the OSLK bit is set. This series applies cleanly to 5.15. Tested on an Ampere Altra machine with the included selftests patches. Additionally, I single-stepped a guest using kvmtool to make sure userspace debugging is still working correctly. [v1]: http://lore.kernel.org/r/20211029003202.158161-1-oupton@google.com v1 -> v2: - Added OSLSR_EL1 to get-reg-list test - Added test cases to debug-exceptions test - Scrapped the context switching of OSLSR_EL1 - Dropped DFR0 changes, to be addressed in a later series Oliver Upton (6): KVM: arm64: Correctly treat writes to OSLSR_EL1 as undefined KVM: arm64: Stash OSLSR_EL1 in the cpu context KVM: arm64: Allow guest to set the OSLK bit KVM: arm64: Emulate the OS Lock selftests: KVM: Add OSLSR_EL1 to the list of blessed regs selftests: KVM: Test OS lock behavior arch/arm64/include/asm/kvm_host.h | 5 ++ arch/arm64/include/asm/sysreg.h | 6 ++ arch/arm64/kvm/debug.c | 20 ++++-- arch/arm64/kvm/handle_exit.c | 8 +++ arch/arm64/kvm/sys_regs.c | 70 ++++++++++++++----- .../selftests/kvm/aarch64/debug-exceptions.c | 58 ++++++++++++++- .../selftests/kvm/aarch64/get-reg-list.c | 1 + 7 files changed, 144 insertions(+), 24 deletions(-) -- 2.33.1.1089.g2158813163f-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm